High-voltage fuse construction with transient grounding feature



June 8, 1965 c. H. WALSH ETAL 3,188,430

HIGH-VOLTAGE FUSE CONSTRUCTION WITH TRANSIENT GROUNDING FEATURE FiledJan. 2, 1962 VVII/IIIIIIIII INVENTORS CARROLL l-LWALSH AGENT UnitedStates Patent @fifice 3,188,430 i a tented June 8, 1965 3,188,430HIGHeVOLTAGE. FUSE. CONSTRUCTION 1TH TRANSIENT GRUUNDIWG FEATURE CarrollH. Walsh and Raymond W.Toler, both Arkansas Power & Light Co Pine Bluff,Ark. Filed Jan 2, 1%2, Ser. No. 163,582 3 Claims. c1. Milk-414) Thisinvention relates generally to fuses for electric circuits, and moreparticularly to a fuse suitable for use in connection with high-voltagetransmission circuits, such as those operating at alternating currentvoltages of 115 kv. or higher. 2

The invention herein embodys certain elements in common with theconstruction shown in Patent No. 2,945,108, dated July 12, 1960, andissued to one of the inventors herein, being distinguished therefrom bya new concept enabling operation in a simpler, less expensive and moreefiectivema'nner. However, the construction herein is intended andsuitable for operation in connection with the commonly-usedneutral-grounded electric transmission system illustrated in theabove-mentioned patent.

Among the objects of the present invention are (l) the provision of afuse which will rupture upon passage of a predetermined currenttherethrough and in response to such rupture will subject the connectedcircuit to only a short-time transient fault; (2) the provision of afuse construction requiring after operation the replacement of only onesmall and inexpensive fuse link, all of the other components beingsuitable for repetitive operation; (3) a construction embodying meansfor guiding a re-usable fuse terminal member along a predetermined pathto a final blown latched position and (4) a construction capable ofelongating the arc attending the fusing of the fuse link to a transferpoint for causing the transient fault on the connected circuit andconsequent extinguishrnent of the arc. Otherobjects will become obviousor pointed out hereinafter. l V V In the drawing:

FIG. 1 is an isometric view of the invention in the normal operatingposition.

FIG. 2 is a fragmentary view of a fuse link suitable for use in thedevice, shown partly in section.

Referring first to FIG. 1 of the drawing, a metal base 10, which incommon practice in high voltage installations is maintained at groundpotential, as by means of the connection to ground indicatedsymbolically at 28, has mounted thereon near its ends the insulatorstacks 11, the height of the stacks being related to thevoltage-to-ground rating of the device. One of the insulator stacks 11has rigidly mounted at its top a source terminal pad 14 and an integrallaterally extending conducting member 16;

, similarly, the other insulator stack 11 supports the load terminal pad13 and the laterally extending conducting member 15. The conductingmembers 15 and 1 6 preferably extend outwardly in parallel relationshipin the same directon and are of substantially equal length.

A first relatively fixed fuse terminal member 17, also of conductingmaterial, is rigidly secured to the outer end of the conducting member15, extending upwardly therefrom and longitudinally with respect to thebase 10, and is provided at its outer end with the fuse terminalfastener 19. A second swingably movable fuse terminal member 18 ispivotally mounted by means of the hinge 31 at the outer end of the otherconducting member 1a, and normally extends toward and in spacedrelationship with respect to the first terminal member 17, beingprovided at its outer end with the fuse terminal fastener 24) and thearcing tip 37.

retaining clip of latch 33, the latter extending downwardly At thehinged end of the fuse terminal member 18 a I clamp 34 rigidly fastensthe resilient motion limiting and from the outer end of the conductingmember 16 and in the path of movement of the swingably movable fuseterminal member 18. A spring 32, fastened at its respective ends to theretaining clip 33 and the movable fuse terminal member 18, continuouslyurges the latter toward swingable movement, thismovement being normallyrestrained by the fuse link 23, bridging the space between andmechanically joining the adjacent ends of the fuse terminal members 17and 18.

An inexpensive fuse link having requisite mechanical strength andeffective corona shielding is satisfactory for use in the device. FIG. 2illustrates one structure which has proven satisfactory,being formedfrom aluminum stranded cable indicated by the end portions 25 and 26,with strands cut away to provide the single strand fusible element 27.The insulating tube 24 mechanically joins the ends portions, beingpressed thereon, and any conducting material having suitable weatheringqualities will provide effective corona shielding.

Near the midpoint of the base 10 is mounted the insulator 12, whichextends upwardly therefrom fora relatively short distance in comparisonuto the height of the insulator stacks 11, and'supports, at its upper endby means of the clamp 22, the transversely extending conducting member21 in spaced insulated relationship with respect to the fuseterminal'members 17 and 18. 'The conducting member 21 is positioned veryclose to but not neces'sarily'in the path of movement of theouter end ofthe swingable fuse terminal member 18, and is grounded as indicate-dbythe symbolic ground 30 through the primary winding of the currenttransformer 29.

When connected for normal operation, a source conductor extending from anormally grounded source is connected to the source terminal pad 14, andthe current path through the'devic e'is sequentially through theconducting member 16, the movable fuse terminal member 18, the fuse1ink23, the fixed fuse terminal member 17 and the conducting'member' 15to the load terminal pad 13.

Upon passage'of a currentsufiicient to fuse the fusible element 27,theheat from the consequent arc causes fracture of the fuse link housing,the fuse link being of inexpensive, non-arc-xtinguishing construction,and the arc continues to play between the spaced fuse terminal members17 and 18. Concurrently the movable fuse terminal, under the bias of thespring 32, swings downwardly and thus elongates the arc until the arcingtip 37 reaches a point in its path of movement closely adjacent to thegrounded conductor 21, illustrated by the broken line designated by thenumeral 35. At this point the arc is intercepted by the conductor 21,being transferred thereto from the fuse terminal member 17. Aline-to-ground fault is thus impressed upon the connected sourcecircuit, causing protective equipment to open the circuit to extinguishthe are, following which the circuit may be reclosed automatically, allin accordance with comm-on practice. During this interval, the movablefuse terminal member continues its swingable movement to the positionindicated by the broken line numbered 36, at which point the movement islimited and the fuse terminal member latched by engagement with theresilient jaws of the clip 33.

It will be apparent that the passage of line-to-ground current throughthe current transformer 29 may be utilized to cause operation of variousassociated equipment, such as high or low tension circuit breakers andalarm circuits, as desired, or as specifically illustrated intheabove-mentioned Walsh patent in connection with polyphase circuits.

The fuse terminal member 13 is of course energized at line potentialfollowing reclosure of the connected circuit,

and the latch clip 33 effectively holds this member in insulated spacedrelationship with both the grounded conductor 21 and the grounded base10, thereby precluding circuit interruptions which might otherwiseresult from a freely swinging fuse terminal member. The only replacementnecessary following operation of the device is the small and inexpensivefuse link, and this low re-fusing cost is equally available, forexample, to all transmission line voltages from 115 kv. to 460 kv.

The foregoing description is intended to be illustrative, and referenceis made to the appended claims to ascertain the scope of the invention.

We claim:

1. A high-voltage fuse construction comprising a conducting base,

insulating means mounted on said base,

spaced insulated load and source conducting members carried by saidinsulating means,

a fixed fuse terminal member mounted on the load conducting member,

' a swingably movable fuse terminal member hinged at one end on saidsource terminal member and extending toward said fixed fuse terminalmember in spaced relationship therewith,

means biasing said swingably movable fuse terminal member for swingablemovement along a predetermined path away from said fixed fuse terminalmember,

a fuse link bridging the space between said fuse terminal members andnormally restraining movement of said movable fuse terminal member,

said fuse link when unfused normally electrically connecting the fuseterminal members and upon fusing releasing the movable fuse terminalmember for movement in response to the are initiated by the fusing ofsaid fuse link and thereby elongating the said fuse link when unfusednormally electrically conmeeting the fuse terminal members and uponfusing releasing the movable fuse terminal member for movement inresponse to the are initiated by the fusing of said fuse link, saidmovement concurrently elongating the are along the predetermined path ofmovement of the unhinged end of said movable fuse terminal member,

additional insulating means mounted on said base,

and a grounded conducting member carried by said additionalinsulating'means,

said grounded conducting member extending to a point adjacent to andspace from the path of movement of the unhinged end of said'swingablymovable fuse terminal member.

3. The construction recited in claim 2, including latch means mounted atthe hinged end of said swingably movable fuse terminal member andpositioned in the path of arc along the path of'movement of the unhingedend 7 i adjacent to and spaced from the path of movement 7 a of theunhinged end of said swingably movable fuse terminal member.

2. A high-voltage fuse construction comprising a conducting base,

insulating means mounted on said base,

movement and limiting the movement thereof,

said latch means holding said movable member in the limited positionfollowing its movement thereto.

References tCited by the Examiner UNITED STATES PATENTS 438,394 10/90White 200 X 607,251 7/98 Lewis. 7

2,272,370 2/42 FOX 200117 2,498,575 2/50 Pittman 200l13.3

7 2,945,108 2/60 Walsh 200-114 BERNARD A. GILHEANY, Primary Examiner;

1. A HIGH-VOLTAGE FUSE CONSTRUCTION COMPRISING A CONDUCTING BASE,INSULATING MEANS MOUNTED ON SAID BASE, SPACED INSULATED LOAD AND SOURCECONDUCTING MEMBERS CARRIED BY SAID INSULATING MEANS, A FIXED FUSETERMINAL MEMBER MOUNTED ON THE LOAD CONDUCTING MEMBER, A SWINGABLYMOVABLE FUSE TERMINAL MEMBER HINGED AT ONE END ON SAID SOURCE TERMINALMEMBER AND EXTENDING TOWARD SAID FIXED FUSE TERMINAL MEMBER IN SPACEDRELATIONSHIP THEREWITH, MEANS BIASING SAID SWINGABLY MOVABLE FUSETERMINAL MEMBER FOR SWINGABLE MOVEMENT ALONG A PREDETERMINED PATH AWAYFROM SAID FIXED FUSE TERMINAL MEMBER, A FUSE LINK BRIDGING THE SPACEBETWEEN SAID FUSE TERMINAL MEMBERS AND NORMALLY RESTRAINING MOVEMENT OFSAID MOVABLE FUSE TERMINAL MEMBER, SAID FUSE LINK WHEN UNFUSED NORMALLYELECTRICALLY CONNECTING THE FUSE TERMINAL MEMBERS AND UPON FUSINGRELEASING THE MOVABLE FUSE TERMINAL MEMBER FOR MOVEMENT IN RESPONSE TOTHE ARC INITIATED BY THE FUSING OF SAID FUSE LINK AND THEREBY ELONGATINGTHE ARC ALONG THE PATH OF MOVEMENT OF THE UNHINGED END OF SAID MOVABLEFUSE TERMINAL MEMBER, ADDITIONAL INSULATING MEANS MOUNTED ON SAID BASE,AND A GROUNDED CONDUCTING MEMBER CARRIED BY SAID ADDITIONAL INSULATINGMEANS, SAID GROUNDED CONDUCTING MEMBER EXTENDING TO A POINT ADJACENT TOAND SPACED FROM THE PATH OF MOVEMENT OF THE UNHINGED END OF SAIDSWINGABLY MOVABLE FUSE TERMINAL MEMBER.